Skill mastery is achieved by reaching level 99 in a skill. To reach level 99, 13,034,431 experience points is needed in a skill.

A player gaining level 99 in a skill.

Once players reach level 99 in a skill, special fireworks will appear in place of the regular set of fireworks usually seen when levelling up. Once players reach the max total level, a different set of fireworks will appear as well.

Players can purchase a Cape of Accomplishment for a skill after reaching level 99 in the skill, for a fee of 99,000 coins. All skill capes come with a corresponding hood and a special emote. Capes become trimmed if a player has two or more maxed levels.